The present invention relates to a monitoring apparatus for cardiopulmonary resuscitation which, in order to enable a rescuer or the like to perform an optimum cardiac massage maneuver when, for example, cardiopulmonary resuscitation is executed, monitors the massage.
In cardiac massage executed in cardiopulmonary resuscitation, conventionally, it is said that a compression displacement of about 4 to 5 cm is appropriate. Related-art apparatuses are known which determines whether the massage is optimally performed or not, and which informs a rescuer or the like of the determination. In several related-art apparatuses, one of or a combination of one or more of signals obtained from force, displacement, velocity, and acceleration sensors are used. For example, there is a related art in which a compression displacement is obtained by double integration of an acceleration, and an influence of common mode noises which are superimposed on the compression displacement because of relationships with a force is eliminated (see JP-T-2010-509014).
There is also a related art in which a rigidity function is obtained from a force and a displacement, and it is determined from its non-linearity whether a compression displacement is appropriate or not (see EP1997469A1). In the related art, in order to correctly obtain the rigidity function, the damping force component (viscosity component) which is proportional to the velocity is previously subtracted.
On the other hand, it is known that the thoracic which is an object of a compression in executed cardiac massage has viscoelasticity characteristics (Bankman et al IEEE TRANSACTIONS ON BIOMEDICAL ENGINEERING, VOL. 37, NO. 2, FEBRUARY 1990, P 211-217). Here, the viscosity is caused by movement of the organs in the thoracic due to the compression. In the case where an appropriate compression is performed, the viscosity is caused in addition to the elasticity.
In the relevant technique disclosed in JP-T-2010-509014, however, the viscosity of the chest which is the compression object is not considered in the determination whether a cardiac massage maneuver which is appropriate in relationships of the displacement and the force is performed or not. In the related art disclosed in EP1997469A1, the viscosity component is subtracted, and therefore the viscosity of the chest is not considered in the determination whether a cardiac massage maneuver is performed or not.
As described above, the thoracic which is the compression object has viscoelasticity characteristics, and hence the determination in which this is not considered is forced to be incorrect. In the case where cardiac massage for cardiopulmonary resuscitation is performed on a soft bed or in a rolling vehicle interior, for example, there is a possibility that it is impossible to determine whether the massage is appropriate in relationships of the displacement and the force or not.